Currently, three-dimensional CAD (Computer Aided Design) systems are used in the development of various kinds of mechanical products. A three-dimensional CAD system models the shape of a mechanical product by accurately defining that shape mathematically. Because the three-dimensional CAD system mathematically and precisely defines the shape of the mechanical product, the three-dimensional CAD system is able to accurately express the static assembled state, however, on the other hand, is not able to express movement of an object well.
However, in the work of assembling the mechanical product, movement of the parts and units are both involved. Many mechanical products have movable parts. Therefore, the verification that it is able to assemble the mechanical product without any problems and that the movable parts function properly is an important point in the design process. When attempting to use the three-dimensional CAD system to carry out this kind of verification concerning the movable portions, sufficient response speed is often difficult. Therefore, a design verification apparatus such as a digital mockup (DMU) system is now often used.
Similar to the three-dimensional CAD system, a DMU system is a system that generates a product model in the virtual space of the computer, and simulates the functions, ease of assembly, operability and the like of the product. In the DMU system, by greatly improving the operability of the system compared with the three-dimensional CAD system, it is possible to easily perform dynamic verification that involves the movement of the parts and units. By using the DMU system, it becomes possible to discover, in an earlier stage, problems that conventionally were not known without making a prototype.
Currently, in the field related to the three-dimensional CAD and DMU, harness design and verification has gained much attention. A harness is a single or plural electric wires or optical cables that have been processed to form a flexible and deformable part. In order to set the wiring arrangement, it is necessary that both the mechanical design and electrical design be completed to a certain extent, so conventionally, harness design was often postponed until later. Actually, it was often the case that after a prototype was completed, an actual harness was installed in the prototype and the length was adjusted, and problems concerning the harness might be discovered late.
In present-day products in which parts or units are very densely mounted, there is a high possibility that, due to various problems such as having to forcibly bend the harness and poor workability during installation, interference between the harness and other parts or units, major reworking will occur. Therefore, there is a need for harness design and verification to be started at a relatively early stage in the design process.
Recently, some commercially sold three-dimensional CAD systems include functions for supporting harness design. The main objective of these is to carry out modeling by importing design in the electrical system into the three-dimensional CAD system. In other words, the harness shape is created in the three-dimensional CAD system according to a connection list that is created in the design of the electrical system. However, as mentioned above, in the three-dimensional CAD system, dynamically verifying the movement of the harness during assembly or when movable parts move is difficult. Moreover, even when the model of a harness, which was created in the three-dimensional CAD system, is imported into the DMU system, the harness that was created using the three-dimensional CAD system is imported into the DMU system as a rigid body solid model. Therefore, it is not possible to use a simple method to perform verification of the harness as a flexible object in the DMU system.
Incidentally, a technique for performing verification of a harness by defining the harness in a DMU system already exists. In such a DMU system, verification is carried out by defining the harness by the endpoints, the cross sectional shape and the path, and simulating change in the path of the harness when parts and units are moved.
However, because the design of the mechanical products is performed using the three-dimensional CAD system, when a problem concerning the harness is discovered in the DMU system, design changes are performed in the three-dimensional CAD system based on the verification results by the DMU system. However, the design changes using the three-dimensional CAD system while referencing the verification results by the DMU system is very complex work. On the other hand, when performing verification again in the DMU system after the model of the harness has been corrected in the three-dimensional CAD system, a harness is created again in the DMU system.
This becomes very complex work, so preferably it would be possible to convert data from the DMU system to the three-dimensional CAD system, and conversely from the three-dimensional CAD system to the DMU system.
Namely, conventionally, it is impossible to appropriately exchange data of the flexible objects between a design verification apparatus and the three-dimensional CAD system.